This invention relates to a process for reheating flue gases after wet cleaning.
Cleaned flue gases normally accumulate as steamsaturated gases with temperatures of from 40.degree. to 55.degree. C. after wet cleaning processes for the removal of sulfur and/or nitrogen compounds. Before being let off through a stack, however, these gases have to be heated to at least 72.degree. C. This heating preferably takes place in heat exchangers using the heat content of the crude gas. The attendant problems caused by corrosion and contamination are known (cf. "Dokumentation Rauchgasreinigung", VDI-Verlag, Sept. 1985). Even more problematical is the heating of wet-desulfurized flue gases to 100.degree.-140.degree. C. to denitrogenize them on active carbon catalysts.
In cases where the gases are reheated in a regenerative heat exchanger with a rotating storage medium (gas preheating device), large temperature differences have to be maintained between the hot untreated gas and the reheated clean gas. The unavoidable leakage losses are a particular disadvantage.
High-grade primary energy in the form of fuel gas or oil is required for heating of the clean gas by means of burners.